Ophthalmothule (meaning "eye of the north"), was a cryptoclidid plesiosaur dating to the latest Volgian (around the Jurassic-Cretaceous boundary), found in the Slottsmøya Member Lagerstätte of the Agardhfjellet Formation in Spitsbergen. The type species is O. cryostea.
Description
Opthalmothule was a medium-sized plesiosaur, measuring long. It was noted to have unusually large eye sockets, which suggests a paleobiological specialization, such as deep water and/or nocturnal hunting. Along with Abyssosaurus, it is one of the youngest cryptoclidids known from boreal regions. The holotype is known from skeletal material that includes a complete cranium and a partial mandible, a complete and articulated cervical vertebrae, a set of pectoral and anterior to middle dorsal series, and the pectoral girdle and anterior humeri.